PREVIOUS PAGENEXT PAGE Electric and Magnetic Fields FACTS W E S T E R N A R E A P O W E R A D M I N I S T R A T I O N NEXT PAGE PREVIOUS PAGENEXT PAGE 1 PREVIOUS PAGENEXT PAGE 10 22 10 20 10 18 10 16 10 14 10 12 10 10 10 8 10 6 10 4 10 2 0 HZ RadiationIonizing Gamma rays X-rays Visible light 60 Hz and 2,450 MHz (inside oven) 800- 900 MHz 15-30 kHz and 50-90 Hz 60 Hz Direct current Electromagnetic Spectrum Frequency is shown in Hertz (Hz). 1 Hz = 1 cycle per second. (Note that 10 4 means 10x10x10x10 = 10,000 Hz, etc.) kHz = kilohertz = 1000 Hz, MHz = megahertz = million Hz. EMF Units Electric Fields Usually measured in volts per meter (V/m) For large elds the units usually used are: 1 kilovolt per meter (kV/m) = 1,000 volts per meter Magnetic Fields Usually measured in milliGauss (mG) Other units sometimes used: 1 microTesla = 10 milliGauss 1 Amp/meter = 0.1257 milliGauss PREVIOUS PAGENEXT PAGE 1 PREVIOUS PAGENEXT PAGE E lectric power lines are familiar to all of us. They have dif- ferent shapes, different sized poles and varying numbers of wires. We may not be able to guess how much power they carry, but we all know what they do: they bring electric power to our homes and businesses. Many of the dramatic improvements in health, safety and quality of life that we benet from today could not have hap- pened without a reliable and affordable electric supply. But could electricity be bad for our health? Electric and magnetic elds are present wherever electricity is used. Do these elds cause cancer or any other diseases, as some have suggested? These important and serious questions have been investigated thoroughly during the past three decades. Several tens of millions of dollars have been spent worldwide. Research on EMF still continues because no clear answers have been found. The balance of scientic evidence to date indicates that these elds do not cause disease. This discussion outlines the EMF issue, summarizes the research conducted to date, and describes what Western Area Power Administration is doing to address concerns about EMF. 2 PREVIOUS PAGENEXT PAGE 3 PREVIOUS PAGENEXT PAGE Electric and Magnetic Fields EMFs are produced both naturally and as a result of human activity. The earth has both a magnetic eld produced by currents deep inside the molten core of the planet, and an electric eld produced by electrical activity in the atmosphere, such as thunderstorms. A primary characteristic of any eld is the frequency. The frequency describes how rapidly an electric or magnetic eld oscillates, or cycles back- ward and forward every second, and is measured in hertz. The earth’s electric and magnetic elds do not oscillate. They are called static elds and have a frequency of 0 Hz. Electricity produced in North America produces elds at a frequency of 60 Hz, or 60 cycles per second, and are known as “extremely low frequency” or “power frequency” elds. Fields at that frequency carry very little energy and are only one small part of the electromagnetic spec- trum that ranges from elds at a frequency of 0 Hz to frequencies in excess of trillions of Hz. Computers, radios, televisions, cellular telephones, micro- wave ovens, X-ray equipment and other devices we use daily operate using frequencies within this spectrum. The science and effects of higher frequency elds are quite different from the 60Hz elds this brochure focuses on. Power frequency electric and magnetic elds occur through hu- man activity wherever electricity is generated, transmitted and used. The Difference Between Electric and Magnetic Fields Electric elds Electric elds are produced by voltage. Voltage is the pressure behind the ow of electricity. It can be compared to the pressure of water in a hose. Voltage creates electric elds around any electrical device that is plugged in—even if it is not operating. For instance, plugging a lamp or hair dryer Electromagnetic Waveform Electromagnetic waveform 1 cycle, 1 wavelength 2 PREVIOUS PAGENEXT PAGE 3 PREVIOUS PAGENEXT PAGE into a wall socket applies voltage to the cord, surrounding it with an elec- tric eld. Electric elds are strongest closest to the source and with higher voltages, but decrease rapidly within a short distance from the source. Walls, roofs, trees and vegetation also weaken or shield electric elds. Electric elds are measured in volts per meter. Magnetic elds Magnetic elds are produced by current, which is the ow of electric- ity. Current is measured in amperes, or amps, and is similar to the volume of water owing in a hose when the nozzle is open. Current must be owing before magnetic elds can be produced. For example, turning on an elec- tric appliance causes magnetic elds to surround the cord and appliance. Magnetic elds are strongest closest to the source, and increase with higher current ow; they also decrease with distance from the source. Unlike electric elds, magnetic elds are not affected by walls or trees, and primarily depend on distance from and strength of the source. Magnetic elds are commonly measured in milliGauss (mG) and in microTeslas (µT). Electric fields Magnetic Fields 1. Produced by voltage. Lamp plugged in but turned off. Voltage produces an electric field. 2. Measured in volts per meter (V/m) or in kilovolts per meter (kV/m). 1 kV = 1000V 3. Easily shielded (weakened) by conducting objects like trees and buildings. 4. Reduced in strength with increasing distance from the source. 1. Produced by current Lamp plugged in and turned on. Current now produces a magnetic field, also. 2. Measured in gauss (G) or tesla (T) 1 milligauss (mG) = 0.1 microtesla (µT) milli (m) = 1 thousandth micro (µ) = 1 millionth. 3. Not easily shielded (weakened) by most materials. 4. Reduced in strength with increasing distance from the source. 4 PREVIOUS PAGENEXT PAGE 5 PREVIOUS PAGENEXT PAGE Exposure Standards and Guidelines It is not known if any EMF levels are unsafe. Some nongovernmental organizations have set advisory limits as a precautionary measure based on the knowledge that high levels of elds (more than 1,000 times the EMF found in typical environments) may induce currents in cells or stimulate nerves. The International Commission on Non-Ionizing Radiation Protection has established a continuous magnetic eld exposure limit of 0.833 Gauss (833 mG) and a continuous electric eld exposure limit of 4.2 kV/m for mem- bers of the general public. The American Council of Governmental Industrial Hygienists publishes Threshold Limit Values for various physical agents. The TLV for occupational exposure to 60 Hz magnetic elds has been set as 10 G (10,000 mG) and 25 kV/m for electric elds. Several states have set guidelines for electric and magnetic eld levels that must be met for newly constructed transmission lines. These levels at the edge of right-of-way are about 2 kV/m Typical 60 Hz magnetic eld levels from some common home appliances Magnetic eld 6 Inches from appliance (mG) Magnetic eld 2 feet away (mG) Electric shaver 100 - Vacuum cleaner 300 10 Electric oven 9 - Dishwasher 20 4 Microwave oven 200 10 Hair dryer 300 - Computers 14 2 Fluorescent lights 40 2 Faxogram machines 6 - Copy machines 90 7 Garbage disposals 80 2 4 PREVIOUS PAGENEXT PAGE 5 PREVIOUS PAGENEXT PAGE for electric elds and 200 mG for magnetic elds. In most cases, the values are maximum elds that existing lines produce at maximum load-carrying conditions. Researchers have used 2 mG in several studies as the threshold magnetic eld value to differentiate between average exposed and more exposed persons. This is based on average elds found in homes, and not for any scientic reason. Natural sources The earth’s elds are static, or 0 Hz frequency. The earth’s magnetic eld which everyone is constantly exposed to is about 500 mG. The earth’s electric eld is about 100 V/m, but thunderstorms can temporarily increase the eld in a given location to several thousand V/m. Sources within the home In the home, in addition to the earth’s natural elds, there are power frequency elds. All electric appliances produce electric and magnetic elds with a 60 Hz frequency. Fields are greatest closest to the surface of the cord and appliance and drop rapidly in just a short distance. The average house- hold background 60 Hz magnetic eld is about 1 to 2 mG. The average back- ground 60 Hz electric eld is 1 to 20 V/m. Typical field level 6 inches 2 feet 40mG 2mG 6 PREVIOUS PAGENEXT PAGE 7 PREVIOUS PAGENEXT PAGE Overhead lines All overhead lines produce elds. The elds are usually the highest directly under the lines and fall rapidly with distance to the sides of the line. Actual eld strengths will, of course, vary depending on the height of the conductors from the point of measurement. Typical 60 Hz electric and magnetic eld levels from overhead power lines Line voltage Centerline Approx. edge of right of way 100 feet 200 feet 300 feet 115 kV Electric eld kV/m Magnetic eld mG 1.0 30 0.5 6.5 0.07 1.7 0.01 0.4 0.003 0.2 230 kV Electric eld kV/m Magnetic eld mG 2.0 57.5 1.5 19.5 0.3 7.1 0.05 1.8 0.01 0.8 500 kV Electric eld kV/m Magnetic eld mG 7.0 86.7 3.0 29.4 1.0 12.6 0.3 3.2 0.1 1.4 Electric elds from power lines are relatively stable because voltage does not change. Magnetic elds uctuate greatly as current changes in response to changing load. The magnetic elds above are calculated for 321 power lines for 1990 mean loads.                               6 PREVIOUS PAGENEXT PAGE 7 PREVIOUS PAGENEXT PAGE Underground lines Underground lines can produce higher magnetic elds directly above them than an overhead line would produce at ground level, because the buried cable is closer to the ground surface. Magnetic elds fall away more rapidly than from overhead lines because of some shielding from the earth. There are no external electric elds produced because of the shielding from the earth. Underground lines are more expensive to install and more difcult and expensive to repair than overhead lines. Because of heat generated at higher voltages, most underground cables are lower voltage distribution lines, such as those that provide power to residential neighborhoods. Substations EMFs are produced within electric substations, but due to the spacing of electrical equipment measured eld strengths are low outside the fence line. Fields close by a substation are mainly produced by the entering power lines. Other eld sources We are surrounded daily with elds from many other sources having frequencies different than 60 Hz. These sources include emissions from com- puters, radio and television towers, cellular telephones, weather and air trafc control radar, military and commercial communications systems, household and industrial remote control devices, intrusion detection equipment and many others. Fields from 60 Hz electrical systems are a very small sliver of the total natural and man-made electromagnetic spectrum environment we live in. Stray voltages Sometimes, cattle and dairy farmers express concern about a herd’s be- havior, weight loss or decreased milk production and blame EMFs from near- by transmission or distribution lines. Investigation of the situation normally shows the cause to be stray voltages. Stray voltages are from deteriorating wiring, or defective, or improperly wired or grounded, equipment. While standing on damp earth or other conductive ground, the animal receives a small electric shock when contacting parts of milking equipment, electrically heated or pumped watering facilities or other electric equipment around the farm. Electric companies usually offer stray voltage diagnosis services. 8 PREVIOUS PAGENEXT PAGE 9 PREVIOUS PAGENEXT PAGE Research into Potential Health Effects With any issue that involves human health, it is important that scientic research be conducted to nd out about possible causes, effects and solutions. Three main types of research are being conducted to determine if EMFs could be related to disease. Epidemiology Epidemiology is the study of patterns of disease in populations. Epidemi- ology looks for any statistical link between exposure to EMF and disease in human populations. Concerns about EMFs were rst raised in an epidemio- logical study when two scientists suggested that levels of elds encountered in some homes might lead to childhood cancer. Since then, other diseases in- cluding adult cancers, heart disease, Alzheimer’s disease and depression have been examined to determine if there could be a link between them and EMFs. Epidemiology can only look at populations and observe statistical as- sociations. It cannot eliminate the many other possible factors that could determine the development of diseases and, therefore, cannot prove whether a particular disease is caused by EMFs. About 20 epidemiological studies have been performed looking at the possible link between magnetic elds and childhood leukemia. Several other studies have looked at other diseases in relationship to magnetic elds for the general population and in the workplace. Some studies have found a weak association with magnetic elds, and others have not. Where there is associa- tion suggested, it is usually very near the statistical threshold of signicance. When these studies are repeated, the results are generally not reproduced. Replication of results is a basic test of scientic validity. Research continues to look at magnetic elds until a more certain conclusion can be reached. Very little evidence exists to conrm that electric elds have any as- sociation with childhood cancer, and some research suggests specically they do not. [...]... results of past and ongoing research in this document because of the great amount of information Work conducted by the National Institute of Environmental Health Sciences/Department of Energy EMF Research and Public Information Dissemination Program provides EMF research information and references The publication Electric and Magnetic Fields Associated with the Use of Electric Power, Questions and Answers... plant and animal health Congress mandated in 1992 that Federal agencies and the scientific community research and conduct a comprehensive review of potential EMF effects on health These studies concluded in 1997 that there is only “weak” evidence that magnetic fields increase the risk of cancer and other human disease Scientific research continues on a wide range of questions relating to EMF exposure, and. .. long-term exposure to low fields, exposure to certain transient waves and other kinds of EMFs You may prefer to take low- and no-cost steps to limit your exposure to strong fields as a way to reduce potential risk Some scientists call this “prudent avoidance.” For instance, you might: ■ Move your motor-driven electric clocks or other electrical devices away from your bed ■ Stand away from an operating... exposure to broadcast frequencies and radar, for instance Some scientists have recommended limiting cell phone use as a prudent avoidance measure, however 11 NEXT PAGE PREVIOUS PAGE Western’s EMF Position Western recognizes the public concern over the possible health effects of electric and magnetic fields While primary exposure to EMFs for most people is in the home and at work, Western realizes that... oven or other appliances that use a lot of electricity ■ Sit away from the TV and at least an arm’s length away from the computer screen and processing unit ■ Decide to use a safety razor instead of an electric one While steps like these may lower your exposure to 60 Hz fields, it is far more difficult to limit exposure to EMFs in the rest of the vast electromagnetic spectrum It is virtually impossible... employees, customers and the public EMF measurements will continue to be made upon request ■ Support and participate in scientific research on EMF and monitor results of research activities by utility, government and private groups ■ Pursue and implement alternative design and siting approaches for new and upgraded transmission facilities to reduce the public exposure to EMFs, particularly when the siting... Health Organization is under way, and will likely influence decision making and further research The research is expected to continue for several more years Until conclusive or more specific research results are obtained, Western will continue to take prudent actions regarding EMFs Western will continue to: ■ Provide balanced and accurate information to employees, customers and the public EMF measurements... and Answers prepared under the NIEHS/DOE EMF RAPID program, specifically Chapter 6, National and International EMF Reviews, and Chapter 7, References, supplies a comprehensive summary and listing of research The document is available online at http: //www.niehs.nih.gov/emfrapid Another NIEHS report is Questions and Answers, EMF in the Workplace Additional EMF information resources are available from:... exposure to EMFs, particularly when the siting of the facilities may occur in populated areas Western is committed to providing a safe, healthy environment for our employees and safe, reliable and economic electric energy to our customer and communities 12 NEXT PAGE PREVIOUS PAGE For more information about Western or EMF, call or write your nearest Western office: Corporate Services Office Mailing address:... information resources are available from: California Department of Health Services California EMF Program http://www.dhs.ca.gov/ps/deodc/ehib/emf/general.html Medical College of Wisconsin, Electromagnetic Fields and Human Health http://www.mcw.edu/gcrc/cop/powerlines-cancer-FAQ/toc.html Environmental Health Information Service http://ehis.niehs.nih.gov/ Microwave News http://www.microwavenews.com World . frequency electric and magnetic elds occur through hu- man activity wherever electricity is generated, transmitted and used. The Difference Between Electric and Magnetic Fields Electric elds Electric. frequency describes how rapidly an electric or magnetic eld oscillates, or cycles back- ward and forward every second, and is measured in hertz. The earth’s electric and magnetic elds do not oscillate safety and quality of life that we benet from today could not have hap- pened without a reliable and affordable electric supply. But could electricity be bad for our health? Electric and magnetic